1. Field of the Invention
The present invention relates to an electronic controller mounted in a vehicle.
2. Description of Related Art
An electronic controller mounted in a vehicle includes a housing made of metal and a circuit board accommodated in the housing. Since the circuit board includes a heater element mounted thereon such as a semiconductor switching element, the circuit board has a heat dissipation structure so that heat generated at the heater element is transferred to the housing and is dissipated from the outer face of the housing to the air. For preferable heat transfer from the heater element to the housing and such heat dissipation from the housing to the air, a technique of surface treatment to the housing surface has been proposed.
In a conventional electronic controller, however, the surface treatment is conducted at the housing surface so as to absorb heat radiated from the heater element. In such a configuration, the heater element away from the housing surface or a small surface area of the housing relative to the heater element may lead to insufficient heat transfer from the heater element to the housing.